Balanced rolling piston compressor with central mass reductions for improved compressor stability

Abstract

An electric compressor includes a housing and a compression device. The housing defines an intake volume and a discharge volume. The compression device is a rotary-type compression device configured to compress refrigerant. The compression device includes a piston device including a cylinder and a rolling piston. The cylinder is eccentrically coupled to a drive shaft. The rolling piston has an outer surface in contact with an inner surface of a compression chamber. The rolling piston rotates about the cylinder as the drive shaft and the piston device are rotated by a motor. A vane moveably coupled to the housing and having an end adjacent the compression chamber is biased such that the end of the vane is in contact with the rolling piston as the piston device is rotated by the drive shaft.

What is claimed: 
     
         1 . A compression device located within a compression chamber of an electric compressor, the electric compressor configured to compress a refrigerant and including a housing, a refrigerant inlet port, a refrigerant outlet port, a motor, and a drive shaft, the housing defining an intake volume and a discharge volume and having a center axis, the housing defines the compression chamber, the refrigerant inlet port coupled to the housing and configured to introduce the refrigerant to the intake volume, the refrigerant outlet port coupled to the housing and configured to allow compressed refrigerant to exit the electric compressor from the discharge volume, the motor mounted inside the housing, the drive shaft coupled to the motor and configured to rotate about the center axis, the compression device being coupled to the drive shaft and configured to receive the refrigerant from the intake volume and compressing the refrigerant as the drive shaft is rotated by the motor, the compression device including:
 a piston device including a cylinder and a rolling piston and having a piston center axis, the piston center axis being offset from the center axis, the cylinder being eccentrically coupled to the drive shaft, the cylinder having a circular outer circumference, the rolling piston being tubular and concentric with the cylinder, the rolling piston having an outer surface in contact with an inner surface of the compression chamber, the rolling piston rotating about the cylinder as the drive shaft and the piston device is rotated by the motor, wherein the cylinder has an interior chamber configured to provide the cylinder with a rotational center of mass about the center axis; and, 
 a vane moveably coupled to the housing and having an end adjacent the compression chamber, the vane being biased such that the end of the vane is in contact with the rolling piston as the piston device is rotated by the drive shaft, the housing, piston device, and the vane forming variable sub-chambers within the compression chamber as the piston device is rotated within the compression chamber, wherein refrigerant enters one of the sub-variable sub-chambers from the intake volume, is compressed as the piston device is rotated, and exits the one of the sub-chambers into the discharge volume. 
 
     
     
         2 . The compression device, as set forth in  claim 1 , wherein the cylinder is keyed to the drive shaft via an interference fit. 
     
     
         3 . The compression device, as set forth in  claim 1 , wherein the housing includes a vane slot, the vane being slidably positioned within the vane slot. 
     
     
         4 . The compression device, as set forth in  claim 3 , the vane slot being connected to the discharge volume, the vane being biased towards the piston device by refrigerant within the discharge volume. 
     
     
         5 . The compression device, as set forth in  claim 3 , the housing including a cylinder housing, the vane slot being located within the cylinder housing. 
     
     
         6 . The compression device, as set forth in  claim 5 , the cylinder housing including an internal suction port coupled between the compression chamber and the intake volume and an internal discharge chamber coupled between the compression chamber and the discharge volume, the compression device further including a reed device coupled to the cylinder housing configured to control the release of pressurized refrigerant from the compression chamber via the internal discharge chamber. 
     
     
         7 . An electric compressor configured to compress a refrigerant, comprising:
 a housing defining an intake volume and a discharge volume and having a center axis, the housing further defining a compression chamber;   a refrigerant inlet port coupled to the housing and configured to introduce the refrigerant to the intake volume;   a refrigerant outlet port coupled to the housing and configured to allow compressed refrigerant to exit the electric compressor from the discharge volume; and,   a compression device located within the compression chamber and being coupled to a drive shaft having a center axis, the compression device configured to receive the refrigerant from the intake volume and to compress the refrigerant as the drive shaft is rotated, the compression device including:
 a piston device including a cylinder and a rolling piston and having a piston center axis, the piston center axis being offset from the center axis, the cylinder being eccentrically coupled to the drive shaft, the cylinder having a circular outer circumference, the rolling piston being tubular and concentric with the cylinder, the rolling piston having an outer surface in contact with an inner surface of the compression chamber, the rolling piston rotating about the cylinder as the drive shaft and the piston device is rotated by the motor, wherein the cylinder has an interior chamber configured to provide the cylinder with a rotational center of mass about the center axis; and, 
 a vane moveably coupled to the housing and having an end adjacent the compression chamber, the vane being biased such that the end of the vane is in contact with the rolling piston as the piston device is rotated by the drive shaft, the housing, piston device, and the vane forming variable sub-chambers within the compression chamber as the piston device is rotated within the compression chamber, wherein refrigerant enters one of the sub-variable sub-chambers from the intake volume, is compressed as the piston device is rotated, and exits the one of the sub-chambers into the discharge volume. 
   
     
     
         8 . An electric compressor configured to compress a refrigerant, comprising:
 a housing defining an intake volume and a discharge volume and having a center axis, the housing further defining a compression chamber;   a refrigerant inlet port coupled to the housing and configured to introduce the refrigerant to the intake volume;   a refrigerant outlet port coupled to the housing and configured to allow compressed refrigerant to exit the electric compressor from the discharge volume;   a motor mounted inside the housing;   a drive shaft coupled to the motor and configured to rotate about the center axis; and,   a compression device located within the compression chamber and being coupled to the drive shaft, the compression device configured to receive the refrigerant from the intake volume and compressing the refrigerant as the drive shaft is rotated by the motor, the compression device including:
 a piston device including a cylinder and a rolling piston and having a piston center axis, the piston center axis being offset from the center axis, the cylinder being eccentrically coupled to the drive shaft, the cylinder having a circular outer circumference, the rolling piston being tubular and concentric with the cylinder, the rolling piston having an outer surface in contact with an inner surface of the compression chamber, the rolling piston rotating about the cylinder as the drive shaft and the piston device is rotated by the motor, wherein the cylinder has an interior chamber configured to provide the cylinder with a rotational center of mass about the center axis; and, 
 a vane moveably coupled to the housing and having an end adjacent the compression chamber, the vane being biased such that the end of the vane is in contact with the rolling piston as the piston device is rotated by the drive shaft, the housing, piston device, and the vane forming variable sub-chambers within the compression chamber as the piston device is rotated within the compression chamber, wherein refrigerant enters one of the sub-variable sub-chambers from the intake volume, is compressed as the piston device is rotated, and exits the one of the sub-chambers into the discharge volume. 
   
     
     
         9 . The electric compressor, as set forth in  claim 8 , wherein the housing includes a cylinder housing and a rear head, the discharge volume being formed, at least partially, by the cylinder housing, the rear head, and the refrigerant outlet port. 
     
     
         10 . The electric compressor, as set forth in  claim 9 , wherein the housing includes an inverter cover and a central housing, the central housing and the inverter cover forming an inverter cavity, the electric compressor further including an inverter module mounted inside the inverter cavity and configured to convert direct current electrical power to alternating current electrical power. 
     
     
         11 . The electric compressor, as set forth in  claim 10 , the housing includes a first drive shaft supporting member and a second drive shaft supporting member. 
     
     
         12 . The electric compressor, as set forth in  claim 11 , further including first and second ball bearings located within the first and second drive shaft supporting members configured to receive respective ends of the drive shaft. 
     
     
         13 . The electric compressor, as set forth in  claim 8 , wherein the cylinder is keyed to the drive shaft via an interference fit. 
     
     
         14 . The electric compressor, as set forth in  claim 8 , wherein the housing includes a vane slot, the vane being slidably positioned within the vane slot. 
     
     
         15 . The electric compressor, as set forth in  claim 14 , the vane slot being connected to the discharge volume, the vane being biased towards the piston device by refrigerant within the discharge volume. 
     
     
         16 . The electric compressor, as set forth in  claim 14 , the housing including a cylinder housing, the vane slot being located within the cylinder housing. 
     
     
         17 . The electric compressor, as set forth in  claim 16 , the cylinder housing including an internal suction port coupled between the compression chamber and the intake volume and an internal discharge chamber coupled between the compression chamber and the discharge volume, the compression device further including a reed device coupled to the cylinder housing configured to control the release of pressurized refrigerant from the compression chamber via the internal discharge chamber. 
     
     
         18 . The electric compressor, as set forth in  claim 16 , the cylinder housing includes a lip to assist in properly positioning the rolling piston relative to the cylinder housing. 
     
     
         19 . The electric compressor, as set forth in  claim 16 , further including an inner cover configured to be positioned within central housing adjacent a flange of the central housing. 
     
     
         20 . The electric compressor as set forth in  claim 19 , the inner cover third drive shaft including a third drive shaft supporting member. 
     
     
         21 . The electric compressor, as set forth in  claim 20 , further including a third ball bearing located within the third drive shaft supporting member configured to receive the drive shaft. 
     
     
         22 . An electric compressor configured to compress a refrigerant, comprising:
 a housing defining an intake volume and a discharge volume and having a center axis, the housing including a central housing, a cylinder housing, a rear head, and an inverter cover, the central housing and the inverter cover forming an inverter cavity, the cylinder housing forming a compression chamber and having a vane slot connected to the discharge volume;   a refrigerant inlet port coupled to the housing and configured to introduce the refrigerant to the intake volume;   a refrigerant outlet port coupled to the housing and configured to allow compressed refrigerant to exit the electric compressor from the discharge volume, the discharge volume being formed, at least partially, by the central housing, the rear head, and the refrigerant outlet port;   a motor mounted inside the housing;   an inverter module mounted inside the inverter cavity and configured to convert direct current electrical power to alternating current electrical power;   a drive shaft coupled to the motor and configured to rotate about the center axis; and,   a compression device located within the compression chamber and being coupled to the drive shaft, the compression device configured to receive the refrigerant from the intake volume and compressing the refrigerant as the drive shaft is rotated by the motor, the compression device including:
 a piston device including a cylinder and a rolling piston and having a piston center axis, the piston center axis being offset from the center axis, the cylinder being eccentrically coupled to the drive shaft, the cylinder having an interior chamber configured to provide the cylinder with a rotational center of mass about the center axis, the cylinder having a circular outer circumference, the rolling piston being tubular and concentric with the cylinder, the rolling piston having an outer surface in contact with an inner surface of the compression chamber, the rolling piston rotating about the cylinder as the drive shaft and the piston device is rotated by the motor; and, 
 a vane within the vane slot and having an end adjacent the compression chamber, the vane being biased towards the piston device by refrigerant within the discharge volume such that the end of the vane is in contact with the rolling piston as the piston device is rotated by the drive shaft, the housing, piston device, and the vane forming variable sub-chambers within the compression chamber as the piston device is rotated within the compression chamber, wherein refrigerant enters one of the sub-variable sub-chambers from the intake volume, is compressed as the piston device is rotated, and exits the one of the sub-chambers into the discharge volume.